Danish researchers develop new tooth filling
Researchers at the University of Copenhagen's Niehls Bohr Institute are currently collaborating with dentists and physicists to develop a new type of tooth filling that will be stronger than composite fillings, according to Science Daily.
Composite fillings, usually composed of acrylate compounds, are used because the material is easy to match to tooth color. For the most part, the use of composite fillings has replaced the use of traditional silver amalgam fillings, which contain mercury.
Longer-lasting than composite
The primary disadvantage of composite material is that it does not last as long as amalgam, and requires frequent replacement in patients prone to multiple cavities.
The interdisciplinary research team embarked upon a study to find an easy-to-bind, mercury-free material as strong as composite. The study, published in the journal Scientific Reports, found glass ionomer cement to be a potentially ideal substitute for composite.
Glass ionomer cement carries the unusual property of releasing fluoride, which helps prevent further decay, explained Ana Benetti, dentist and researcher at the Faculty of Health and Medical Science at the University of Copenhagen.
Testing the material
Two types of glass ionomer cement, one blended with an acid mix, were the subjects of the study. The first cement was made by mixing acid and cement powder, then adding water. For the second, researchers added a water-and-acid mixture to the cement powder. Seeking the best substance for mixing the cement - acid or water - they enacted a variety of experiments.
They began the experiment with X-Rays of pulled teeth filled with the cement, using 3-D imaging to look at the porosity of the cement, said Heloisa Bordallo, associate professor and materials researcher at the Niehls Bohr Institute at the University of Copenhagen. The cement's porous nature was not alone an indicator of weakness - the strength of the cement would depend on whether the water or acid bound to the material or moved through its pores.
After using the X-rays for structural observation, the researchers employed neutron scattering to gather more images, so they could identify whether the fillings held any water. If so, the material would not make a good alternative to composite fillings. This technique allowed them to check for the appearance of hydrogen atoms, which would indicate the presence of fluid.
Bordallo and her colleagues found that adding water to an acid-cement mix made a weak filling. The strongest material resulted from mixing acid and water before combining the liquid with the cement powder. But the alternative filling is not yet viable for dental use, and further studies will address the biological structure and binding process of the cement.
What's most promising about the ionomer is that it requires no special equipment for mixing. The possibility of hand-mixing means regions without electricity could also stand to benefit.